Introduction To SMEMA Interface

The conveyors and the SMT Lines machine are SMEMA standardized. SMEMA is the Surface Mount Equipment Manufacturers Association. They Have standardized both the mechanical and electrical interface and it is called SMEMA Interface standard 1.2. The purpose of this standard is to provide an equipment specification for single board transfer manufacturing systems of surface-mounted printed circuit boards.

SMEMA Mechanical Interface:

1.     Conveyor height: Each machine must have the transport conveyor height adjustable from 939.8 to 965.2 mm from the floor to the bottom of the PCB.

2.     Conveyor width:  For equipment with an adjustable conveyor width, the front rail is fixed and the rear rail is adjustable. The range of adjustment will vary with the equipment manufacturer.

3.     Edge clearance: The conveyor should require no more than 3 mm of clear board space at the side edges.

4.     Maximum gap: The maximum gap between the in-line machine track ends is 9.5 mm.

5.     Lead-in:  The minimum lead-in on the track ends of the conveyor is 3.1 mm.

SMEMA Electrical Interface:

There is also a standard for the electrical interfaces between machines of

Different manufactures.

The logic is as follows:

• Board transfer occurs when machine A has a Board available (contact closed), and machine B is Not busy (contact closed).

• The signal BA/NB can occur at anytime, but board transfer does not occur until both contacts are closed.

•  The Board available signal from machine A will remain closed until the board has left machine.

• The Not busy signal will remain closed until the board has arrived at machine B.

• Board transfer cannot occur again until each signal opens for at least 50 ms.

•  Optional: Once both machine A and machine B signals are closed, and the board has neither left A nor arrived at B, an error message will be Generated.